Link Budget Analysis for Line of Sight Communications in D-band: Radio Coverage vs. Antenna Gain

In this paper a procedure to determine the appropriate antenna type and specific gain range, for line of sight (LOS) communications scenarios in D-band (110-170GHz) is presented. The procedure is performed via link budget analysis method for all four channels of D-band, centered at 132GHz, 144.75GHz, 157.75GHz, 170.9GHz respectively, and consists of the following steps: a) link budget analysis with aim to create results of radio coverage distance range per required gain, b) define antenna required gain for specific channel and digital modulation scheme (128QAM and 256QAM), c) increase required gain considering losses of Ortho-Mode Transducer (OMT) or polarizer in the feeding network, d) adjust final selected required gain considering extra rain attenuation losses, e) select appropriate antenna type by combining a classification of antennas with distance range gain results. This procedure constitutes a basic step preparing the antenna design (antenna pre-design) and can be utilized to assess communication system parameters and their effect into link budget for LOS communications. The antenna pre-design is validated through a realistic scenario selected for the 132GHz, with 128QAM and 256QAM digital modulations and for 100m LOS, using a 30cm reflector diameter, Cassegrain antenna design appropriate for gain above 45 dBi.